Butadiene-styrene rubbery copolymer stabilized with antimonyl-4,6 dimethyl catecholate



Patented July 10, 1951 MER STABILIZED WITH ANTIMONYL-lfi DIIME'IHYL CATECHOLATE Harry E. Albert and George E. P. Smith, In,"

Akron, Ohio, assignors to The Firestone Tire & Rubber Company, Akron, Ohio, a corporation of Ohio No Drawing. Application November 21, 1950, Serial No. 196,934. In Canada October as, 1949 2 Claims. (Cl. 260-4575) 1 This invention relates to the stabilization of the rubber-like polymerizate of 1,3-butadiene and styrene with antimonyl-4,6-dimethyl catecholate.

The application is a division of Albert and Smith application Serial No. 84,493 filed March 30, 1949. The invention includes the stabilization of the uncured copolymer, the stabilization of the cured copolymer and the process of stabilization. A particular application of the invention is in the stabilization of compounds of the rubber-like copolymer which are white or pastel shadesfor example, the white sidewalls of tires, etc.because the stabilizers of this invention do not discolor. Difficulty has been experienced in finding a satisfactory non-discolorizing stabilizer. for GR-S. Penyl-beta-naphthylamine, which is the most widely used stabilizer for GR-S, discolors badly. I The antioxidant or stabilizing efieot of antiwas then compounded according to the following fgrniizula. Various tests were run on these two 5 s.

. FORMULA The stocks were cured 50 minutes at 300 The vulcanizates were tested in a iadeometer and under a General Electric sunlamp at a distance monyl-4,6-dimethyl catecholate was compared 2 oi. seven inches.

TABLE III Artificial exposure tests Fadeometer at 125 0. Bunlamp Stabilizer 5 Hours Hours 8 Hours 16 Hours Aggifiiozgyl-afi-dimethyl cate- Slightly discolored Cream Very slightly discolored-.- Light tan.

Stabilizer- A (control) Tan Light brown Lighttan Dark tam,

that of a commercial stabilizer identified as The latex was coagulated Natural exposure tests were conducted on tapered dumb-bell strips of stock cured 50 minutes at 300 F. and stretched 12 per cent. The gas? were conducted in Akron, Ohio, starting TABLE I.

Copolymer aging After Heat-aging at 110 C. After Drying stabmm Hours at 75 0.

One Day Two Days Four Days antimonyl-4,G-dimethylcateholate No deterioration.. Un h d U h Stabilizer A (control fin don ange 131cc anged i l lfii wt up.

The data for the above table were obtained by a TABLE m manual test of the various samples. These data show that the antimonyl compound is superior Natural exposure tests to Stabilizer A as an antioxidant for the copoly- Stabilizer 1 Month 2 Months Two per cent of ant1monyl-4,6-d1methyl catecholate and 2 per cent of Stabilizer A were added 6 AntimmyMwmethy; camnolate whmm whim to GR-S latices which were then coagulated with Stabilizer A (control) Light low-iron aluminum sulfate and each ooagulum with stirring, the following ingredients at 107 C. for nine hours:

6.5 moles NaOH 1.0 moles BaCh.2H:O 0.75 moles 2-bromo-4,6-dimethylphenol 22 a. cmCl:

1000 c. c. H20

x The reaction product was acidified with hydrochloric acid. extracted with ether, the ether evaporated and the residue was vacuum distilled at 4 mm. The major portion of the product dis'- tilled at 118.5-119 C. as a red liquid. The prod-' not was then recrystallized from petroleum etherbenzene to yield the pure 4,6-dimethyl catechol. melting at 64-66 c.

The antimony salt of the catechol so pro- 3 duced was prepared by heating 16 grams 01' the 4,6-dimethyl catechol with 8 grams of water on a steam plate and adding to the mixture 17.8 rams of SbzOaI After one hour the reaction mass had solidified. The mixture was heated for another 1.5 hours to complete the reaction.

The product was obtained as 29.5 grams of a solid, which was ground to a gray-white powder for use in the stabilizing tests disclosed above.

What we claim is:

styrene stabilized with a small amount of antimonyl-4,6-dimethyl eatecholate.

2. The process of drying rubber-like copolymer of 1,3-butadiene and styrene which comprises heatingthe same admixed with antimonyl-4,6-

v dime'thyl catecholate as a stabilizer.

HARRY E. ALBERT. GEORGE E. P. SMITH, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Hunter Nov. 22, 1949 Number 1. Rubber-like copolymer of 1,3-butadiene and 

1. RUBBER-LIKE COPOLYMER OF 1.3-BUTADIENE AND STYRENE STABILIZED WITH A SMALL AMOUNT OF ANTIMONYL-4,6-DIMETHYL CATECHOLATE. 